1. Field of the Invention
The present invention relates to a method of manufacturing a thin film transistor array panel.
2. Description of Related Art
A flat panel display such as a liquid crystal display (LCD) and an organic light emitting display (OLED) includes a thin film transistor array panel including a plurality of pixel electrodes, a plurality of thin film transistors (TFTs) connected thereto, a plurality of signal lines connected to the TFTs, a plurality of drivers for driving the display panel, and a controller for controlling the drivers.
The signal lines include gate lines for transmitting gate signals from the drivers to the TFTs and data lines for transmitting data signals from the drivers to the TFTs.
A TFT includes a semiconductor layer of amorphous silicon or polysilicon, a gate electrode connected to the gate line, a source electrode connected to the data line, and a drain electrode connected to the pixel electrode.
A polysilicon TFT, using a polysilicon such as a semiconductor layer, has the relatively high electron mobility by amorphous silicon TFT, and the polysilicon TFT enables the implementation of a chip in glass technique that a display panel embeds its driving circuits.
A TFT including a polysilicon layer usually places the gate electrode on the polysilicon layer and the polysilicon layer includes lightly doped drain (LDD) regions disposed between a channel region and source and drain regions for reducing punch through, etc.
A gate overlapped lightly doped drain (GOLDD) TFT, which has lightly doped drain regions overlapping the gate electrode, is widely used in metal oxide semiconductor (“MOS”) TFT technique, because the GOLDD TFT has a high reliability in comparison with a general LDD TFT, and reduces off current without the drop of on current. Particularly, a TFT having a short channel adopts the GOLDD type rather than the general LDD type on account of the reliability of the TFT due to hat carriers.
However, it is difficult to control a doping concentration with N type impurity in a manufacturing method of the conventional GOLDD structure and to apply an excimer laser annealing process having high activation ratio to such a manufacturing method.